1. Field of the Invention
This invention relates generally to cassette tape recording and/or reproducing apparatus, and more particularly is directed to the provision of such apparatus with an improved automatic shut-off or other mode changing device.
2. Description of the Prior Art
Various mechanical arrangements have been proposed for automatically halting the driving of the tape and reels within a cassette upon the full unwinding of the tape from a supply reel to a take-up reel. One such device, for example, as disclosed in detail in U.S. Pat. No. 3,779,498, having a common assignee herewith, employs a rotary member which always rotates when the tape is running, for example, as in the normal forward mode, but stops when the tape is fully unwound from the supply reel onto the take-up reel, an elongated shut-off lever or plate which is mounted for rotation about the axis of the rotary member and a frictional clutch for urging the shut-off lever to turn with the rotary member so long as the latter is being rotated. A cam is driven from the motor which rotates the capstan and causes a repeated uniform stroke or reciprocating movement of a pawl member so long as the motor is operated. The pawl member is engageable with teeth on a reciprocating slide which is made to undergo a movement sufficient to change-over from the normal forward mode to the stop mode of the apparatus only when the motor continues to operate while the rotary member is halted with the result that the frictional clutch no longer angularly urges the shut-off lever to turn.
The above generally described shut-off device is disadvantageously complicated. For example, such device requires the installation of a frictional ring between the shut-off lever and the associated rotary member, a helical compression spring extending along the axis of the rotary member to urge the shut-off lever and rotary member toward each other with the frictional ring therebetween, and an annular spring seat extending around the axis of the rotary member for retaining the helical spring thereon. Further, this prior shut-off device is disadvantageous in that the frictional ring, helical spring and spring seat or annulus arranged along the axis of the rotary member undesirably increase the dimensions of the device in that direction, and therefore discourage the provision of such a device in portable cassette tape recording and/or reproducing apparatus where miniaturization is generally desirable. Moreover, by reason of the relatively complex construction of the described existing shut-off device, assembling thereof is relatively difficult and increases the cost thereof.